Raspberry PI baby monitor

A simple baby monitor, uses a Raspberry PI + USB webcam to send video/audio, and smartphone or PC with a recent browser to recieve it. No special app is needed.

Technical Details

This service works on Raspberry PI, but can be adopted for a PC with Debian/Ubuntu It is assumed that a webcam with a microphone is attached to USB And supported by linux kernel, creating /dev/video0 and default audio capture device (ALSA)

Install dependencies (Raspberry Pi OS Lite)

# prebuilt Janus dependencies + gstreamer
sudo apt install -y  autoconf automake autogen libtool gengetopt \
             libconfig-dev libmicrohttpd-dev libssl-dev libglib2.0-dev libjansson-dev  \
             gstreamer1.0-tools \
             gstreamer1.0-plugins-good gstreamer1.0-plugins-bad \
             gstreamer1.0-omx-rpi gstreamer1.0-omx-rpi-config  \
             gstreamer1.0-rtsp gstreamer1.0-alsa gstreamer1.0-libav gstreamer1.0-omx  \
             nginx


# all additional libraries will be installed in /opt/janus
PREFIX=/opt/janus

# some libraries need to be compiled from source
# libnice 0.1.16 ( Interactive Connectivity Establishment )

curl https://libnice.freedesktop.org/releases/libnice-0.1.16.tar.gz -o libnice-0.1.16.tar.gz -L
tar xzf libnice-0.1.16.tar.gz
cd libnice-0.1.16
./configure --prefix=$PREFIX 
make
sudo make install # will install into $PREFIX
cd ..

### libsrtp 2.3.0 ( Secure Real-time Transport Protocol )

curl https://github.com/cisco/libsrtp/archive/v2.3.0.tar.gz -o libsrtp-2.3.0.tar.gz -L
tar zxf libsrtp-2.3.0.tar.gz
cd libsrtp-2.3.0
./configure --prefix=$PREFIX --enable-openssl
make 
sudo make install # will install into $PREFIX
cd ..

Compiling Janus-gateway itself

curl https://github.com/meetecho/janus-gateway/archive/v0.10.10.tar.gz -o janus-gateway-0.10.10.tar.gz -L
tar zxf janus-gateway-0.10.10.tar.gz
cd janus-gateway-0.10.10
./autogen.sh
PKG_CONFIG_PATH=$PREFIX/lib/pkgconfig ./configure --prefix=$PREFIX --enable-libsrtp2
make 
sudo make install # will install into $PREFIX

Define janus configuration

Janus WebRTC server will be listening on port 8088(REST API), by default these ports are open to the whole world, so don't run it on your publicly exposed web computer. All other janus plugins are disabled!

sudo cp janus_etc/janus.jcfg janus_etc/janus.transport.http.jcfg janus_etc/janus.plugin.streaming.jcfg  /opt/janus/etc/janus/

Send live stream using hardware acceleration of Raspberry PI

We are going to capture whatever video is coming from /dev/video0 device, by default this is the first web camera attached to the raspberry pi. If you are using RaspiCAM it can also be visible as this device.

gstreamer can capture uncompressed video stream from /dev/video0 and compress it using hardware acceleration on raspberry pi using omxh264enc plugin. We are instructing the camera to capture using 640x480 format with 30 frames per second, and capture audio using first ALSA device (microphone of your webcam) (this command will be run by systemd , using capture.service below):

gst-launch-1.0     \
  -v v4l2src device=/dev/video0 ! \
      video/x-raw,width=640,height=480,framerate=30/1 ! \
      videorate ! videoconvert !\
      omxh264enc target-bitrate=240000 control-rate=variable !\
      h264parse !\
      rtph264pay config-interval=1 pt=96 !\
      udpsink host=127.0.0.1 port=8004 \
    alsasrc device=plughw:1  ! \
      audioresample quality=1 ! \
      audio/x-raw,rate=16000,channels=1 ! \
      opusenc bitrate=10000 ! \
      rtpopuspay ! \
      udpsink host=127.0.0.1 port=8002

On raspberry pi 3 this capture uses approximately 40% of a single cpu core.

If you want to run this on a system without hardware acceleration for h264 encoding (i.e an Intel PC). Then you will have to use software codec, replace omxh264enc with x264enc in the capture.service

Create services for systemctl

sudo cp janus.service /etc/systemd/system/janus.service
sudo cp capture.service /etc/systemd/system/capture.service

sudo systemctl daemon-reload
sudo systemctl enable janus
sudo systemctl enable capture

sudo systemctl start janus
sudo systemctl start capture

Web server setup

We are using NGINX but any HTTPD server will do the job. Copy the contents of html directory into the target location. All the processing will handled by janus and web browser. It is possiblt to use NGINX to serve as a reverse-proxy for Janus control API , if you don't want to expose too many ports.

This will install simple index.html page to the default location of the NGINX server root: The index.html is configured to Janus REST api

sudo cp -r html/* /var/www/html/

NGINX configuration /etc/nginx/sites-enabled/default

...
server {
    ...
        listen 80 default_server;
        listen [::]:80 default_server;
        index index.html;
        
        # reverse proxy setup:
        location /janus-api {
            proxy_set_header X-Real-IP $remote_addr;
            proxy_set_header Host $host;
            proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
            proxy_set_header X-Forwarded-Proto $scheme;
            proxy_http_version 1.1;
            proxy_set_header Upgrade $http_upgrade;
            proxy_set_header Connection "upgrade";
            proxy_set_header Host $host;
            proxy_redirect off;
            proxy_pass         http://127.0.0.1:8088;
        }
    ...
}
...

or just copy required file:

sudo cp nginx/default /etc/nginx/sites-available/default
sudo systemctl reload nginx

It's all done

Navigate to the http://pi.local , or use local IP address of your raspberry pi and start watching the live feed.

Time lag

Around 0.5 sec